Converter bridge arm suitable for high-voltage applications and application system thereof

1. A converter bridge arm suitable for high-voltage applications, which includes an energy storage capacitor and a plurality of reverse conducting switches; wherein, the converter bridge arm is formed by a series connection of an upper telescopic arm, a lower telescopic arm, and an inductor set, wherein the upper telescopic arm and the lower telescopic arm are each formed by a cascading connection of a plurality of symmetrical units; wherein, each symmetrical unit of the plurality of symmetrical units includes a first switch, a second switch, a third switch, a fourth switch and an energy storage capacitor; the first switch and the second switch are connected in series; the third switch and the fourth switch are connected in series; a positive terminal of the first switch is connected with a positive terminal of the third switch to serve as a positive terminal of the symmetrical unit, and a negative terminal of the second switch is connected with a negative terminal of the fourth switch to serve as a negative terminal of the symmetrical unit; the energy storage capacitor is connected between the positive terminal and the negative terminal of the symmetrical unit; a junction between the first switch and the second switch is a second cascading connection terminal of the symmetrical unit, and a junction between the third switch and the fourth switch is a fourth cascading connection terminal of the symmetrical unit; wherein, the cascading connection of the plurality of the symmetrical units includes, between two adjacent symmetrical units, the fourth cascading connection terminal of a former symmetrical unit of the two adjacent symmetrical units is connected with the second cascading connection terminal of a latter symmetrical unit of the two adjacent symmetrical units; wherein, the converter bridge arm further includes a positive terminal and a negative terminal; wherein, a positive terminal and a negative terminal of an uppermost symmetrical unit of the upper telescopic arm, a positive terminal and a negative terminal of a lowermost symmetrical unit of the upper telescopic arm, a positive terminal and a negative terminal of an uppermost symmetrical unit of the lower telescopic arm, and a positive terminal and a negative terminal of a lowermost symmetrical unit of the lower telescopic arm serve as auxiliary terminals of the converter bridge arm; wherein, the second cascading connection terminal is taken as a positive terminal of the converter bridge arm and the fourth cascading connection terminal is taken as a negative terminal of the converter bridge arm; wherein, a neutral point of the converter bridge arm is led from a conjunction between a negative terminal of the upper telescopic arm and a positive terminal of the lower telescopic arm; and wherein, the inductor set is one selected from the following: (1) the inductor set includes one inductor, which is located at any position of the series connection of the upper telescopic arm and the lower telescopic arm; (2) the inductor set includes two inductors, which are located at opposing sides of the neutral point of the converter bridge arm such that the neutral point of the converter bridge arm is disposed between the two inductors; and (3) the inductor set includes a plurality of inductors, each of the plurality of inductors being disposed between two adjacent symmetrical units; wherein, an AC/AC convertor including one or more of the converter bridge arms is connected in one of the following configurations: (a) an alternating current port fed from positive and negative terminals of one converter bridge arm, and another alternating current port led from the neutral point of the converter bridge arm, such that a single AC/AC convertor is formed; (b) a multiphase alternating current port fed from positive and negative terminals of each of the converter bridge arms in accordance with a polygon or star connection method, and another multiphase alternating current port is led from neutral points of each of the converter bridge arms; and (c) positive and negative terminals of a first group of three converter bridge arms are connected with various input phases respectively in accordance with a triangle or star connection method, and positive and negative terminals of a second group of three converter bridge arms are connected with various output phases respectively in accordance with a triangle or star connection method; the neutral point terminals of the first and second groups of three converter bridge arms are connected with primary and secondary windings of a three-phase medium-frequency transformer respectively, such that an electronic transformer is formed.

2. A converter control configuration based on the converter bridge arm according to claim 1 , wherein: terminal voltages (Us) of the symmetrical units in the upper and lower telescopic arms are controlled by regulating drive pulses of all switches, so as to control terminal voltages (Uu) and (Ud) of the upper telescopic arm and the lower telescopic arm; an average current (I PN ) passing between positive and negative terminals of the converter bridge arm is controlled by dynamically regulating a sum of the voltage (Uu) and the voltage (Ud), so as to control an average value of voltage (Uc) of all the symmetrical units in the converter bridge arm; regulation for voltage potential at an neutral point terminal is achieved by complementarily regulating the voltage (Uu) and the voltage (Ud); distribution of currents (I P ) and (I N ) of the upper telescopic arm and the lower telescopic arm is changed by dynamically regulating a relative magnitude of the voltage (Uu) and the voltage (Ud), so as to balance a difference between an average value of the voltage (Uc); and differences of the voltage (Uc) on an energy storage capacitor of the symmetrical units in the telescopic arms are balanced by regulating a relative magnitude of average values of a terminal voltage (Us) of the symmetrical units in the upper telescopic arm and the lower telescopic arm.

3. The converter control configuration according to claim 2 , wherein: the converter control configuration is one selected from followings: (1) a configuration of identical pulse phase is configured for the symmetrical units in a same telescopic arm; (2) a configuration of phase-shift is configured for the symmetrical units in a same telescopic arm; (3) a configuration of a sinusoidal pulse width modulation (SPWM) in which carriers are equally phase-shifted based upon angle of circumference is configured for the symmetrical units in a same telescopic arm, and carriers phases of the corresponding symmetrical units between the upper telescopic arm and the lower telescopic arm are complemented; or (4) a configuration of a three-phase DC/AC, AC/DC converter formed by three bridge arms, six symmetrical units, which are located at same positions of the bridge arms, are grouped and controlled under a sinusoidal space vector pulse width modulation (SVPWM) mode, and modulated carriers of the symmetrical units in the same telescopic arm are equally phase-shifted based upon angle of circumference.

4. A converter bridge arm suitable for high-voltage applications, which includes a plurality of energy storage capacitors and a plurality of reverse conducting switches, each reverse conducting switch includes a switch and a reverse conducting diode connected in parallel; wherein, the converter bridge arm is formed by a series connection of an upper telescopic arm, a lower telescopic arm, and an inductor set, wherein the upper telescopic arm and the lower telescopic arm are each formed by a cascading connection of a plurality of balance units; and the balance unit is a balance asymmetrical unit or a balance symmetrical unit; wherein, the balance asymmetrical unit includes a first switch of the balance asymmetrical unit, a second switch of the balance asymmetrical unit, a third switch of the balance asymmetrical unit, a fourth switch of the balance asymmetrical unit, and an energy storage capacitor of the balance asymmetrical unit; the first switch and the second switch of the balance asymmetrical unit are connected in series; the third switch and the fourth switch of the balance asymmetrical unit are connected in series a positive terminal of the first switch of the balance asymmetrical unit is connected with a positive terminal of the third switch of the balance asymmetrical unit to serve as a positive terminal of the balance asymmetrical unit and also a first cascading connection terminal of the balance asymmetrical unit; a negative terminal of the second switch is connected with a negative terminal of the fourth switch to serve as a negative terminal of the balance asymmetrical unit and a fourth cascading connection terminal of the unit; the energy storage capacitor of the balance asymmetrical unit is connected between the first cascading connection terminal and the fourth cascading connection terminal of the balance asymmetrical unit; a junction between the first switch and the second switch of the balance asymmetrical unit is a second cascading connection terminal of the balance asymmetrical unit, and a junction between the third switch and the fourth switch of the balance asymmetrical unit is a third cascading connection terminal of the balance asymmetrical unit; wherein, the balance symmetrical unit includes a first switch of the balance symmetrical unit, a second switch of the balance symmetrical unit, a third switch of the balance symmetrical unit, a fourth switch of the balance symmetrical unit, a fifth switch of the balance symmetrical unit, a sixth switch of the balance symmetrical unit, a seventh switch of the balance symmetrical unit, an eighth switch of the balance symmetrical unit and an energy storage capacitor of the balance symmetrical unit; wherein, the first switch of the balance symmetrical unit is connected with the second switch of the balance symmetrical unit in series, a junction therebetween is a first cascading connection terminal of the balance symmetrical unit; the third switch of the balance symmetrical unit is connected with the fourth switch of the balance symmetrical unit in series, a junction therebetween is a third cascading connection terminal of the balance symmetrical unit; the fifth switch of the balance symmetrical unit is connected with the sixth switch of the balance symmetrical unit in series, a junction therebetween is a second cascading connection terminal of the balance symmetrical unit; the seventh switch of the balance symmetrical unit is connected with the eighth switch of the balance symmetrical unit in series, a junction therebetween is a fourth cascading connection terminal of the balance symmetrical unit; positive terminals of the first switch, the third switch, the fifth switch, and the seventh switch of the balance symmetrical unit are connected to serve as a positive terminal of the balance symmetrical unit, and negative terminals of the second switch, the fourth switch, the sixth switch and the eighth switch of the balance symmetrical unit are connected to serve as a negative terminal of the balance symmetrical unit; and two terminals of the energy storage capacitor of the balance symmetrical unit are connected between the positive terminal and the negative terminal of the balance symmetrical unit; wherein, the cascading connection of the plurality of balance units includes a plurality of two adjacent units, each two adjacent units includes a former unit and a latter unit, a third cascading connection terminal of the former unit is connected with a first cascading connection terminal of the latter unit, a fourth cascading connection terminal of the former unit is connected with a second cascading connection terminal of the second unit; wherein, a first connection between the former unit and the latter unit is formed with an inductor or a resistor or a parallel circuit of an inductor and a resistor, and a second connection between the former unit and the latter unit is directly connected; wherein, a positive terminal of an outermost balance unit of the cascading connection of the plurality of balance units, and a negative terminal of another outermost balance unit of the cascading connection of the plurality of balance units serve as auxiliary terminals of the converter bridge arm; a second cascading connection terminal of a balance unit is taken as a positive terminal of the converter bridge arm and a fourth cascading connection terminal is taken as a negative terminal of the converter bridge arm; and wherein, a neutral point of the converter bridge arm is a conjunction between a negative terminal of the upper telescopic arm and a positive terminal of the lower telescopic arm; and the inductor set is one selected from the following: (1) the inductor set includes one inductor, which is located at any position of the series connection of the upper telescopic arm and the lower telescopic arm; (2) the inductor set includes two inductors, which are respectively located at opposing sides of the neutral point of the converter bridge arm such that the neutral point of the converter bridge arm is disposed between the two inductors; and (3) the inductor set includes a plurality of inductors, each one of the inductors disposed between two adjacent units.

5. The converter bridge arm according to claim 4 , wherein, the upper or lower telescopic arm is formed by a cascading connection of a plurality of balance asymmetrical units; the cascading connection of the plurality of balance asymmetrical units includes a plurality of two adjacent units; any two adjacent units include a former unit and a latter unit; a fourth switch of the former unit or a first switch of the latter unit is replaced by a replacement diode; the replacement diode has a same polarity as a reverse conducting diode of the fourth switch of the former unit or the first switch of the latter unit being replaced.

6. The converter bridge arm according to claim 4 , wherein, the upper or lower telescopic arm is formed by a cascading connection of a plurality of balance symmetrical units; the cascading connection of the plurality of balance symmetrical units includes a plurality of two adjacent units; any two adjacent units include a former unit and a latter unit; a seventh switch or an eighth switch of the former unit is replaced by a first replacement diode; the first replacement diode has a same polarity as a reverse conducting diode of the seventh switch or the eighth switch of the former unit being replaced; a fifth switch or a sixth switch of the latter unit is replaced by a second replacement diode; the second replacement diode has a same polarity as a reverse conducting diode of the fifth switch or the sixth switch of the latter unit replaced.

7. The converter bridge arm according to claim 4 , wherein, the upper or lower telescopic arm is formed by a cascading connection of a plurality of balance symmetrical units; the cascading connection of the plurality of balance symmetrical units includes a plurality of two adjacent units; any two adjacent units include a former unit and a latter unit; a seventh switch or an eighth switch of the former unit is replaced by a first replacement diode; the first replacement diode has a same polarity as a reverse conducting diode of the seventh switch or the eighth switch of the former unit being replaced; optionally, a fifth switch or a sixth switch of the latter unit is replaced by a second replacement diode; the second replacement diode has a same polarity as a reverse conducting diode of the fifth switch or the sixth switch of the latter unit being replaced; and wherein a wire connection mode of the fifth switch, the sixth switch, the seventh switch and/or the eighth switch replaced by the first and/or the second replacement diode includes: a positive terminal of the fifth switch or a negative terminal of the sixth switch are connected to a second cascading connection terminal, and a positive terminal of the seventh switch or a negative terminal of the eighth switch are connected to a fourth cascading connection terminal.

8. The converter bridge arm according to claim 4 , wherein, the upper or lower telescopic arm is formed by a cascading connection of a plurality of balance asymmetrical units; the cascading connection of the plurality of balance asymmetrical units includes a plurality of two adjacent units; any two adjacent units include a former unit and a latter unit; a third cascading connection terminal of the former unit is directly connected with a first cascading connection terminal of the latter unit, and a fourth cascading connection terminal of the former unit is directly connected with a second cascading connection terminal of the latter unit; and a fourth switch of the former unit or a first switch of the latter unit is omitted.

9. The converter bridge arm according to claim 4 , wherein, the upper or lower telescopic arm is formed by a cascading connection of a plurality of balance symmetrical units; the cascading connection of the plurality of balance symmetrical units includes a plurality of two adjacent units; any two adjacent units include a former unit and a latter unit; a third cascading connection terminal of the former unit is directly connected with a first cascading connection terminal of the latter unit, and a fourth cascading connection terminal of the former unit is directly connected with a second cascading connection terminal of the latter unit; a seventh switch of the former unit or a fifth switch of the latter unit is omitted; and an eighth switch of the former unit or a sixth switch of the latter unit is omitted.

10. The converter bridge arm according to claim 4 , wherein, between a negative terminal of the upper telescopic arm and a positive terminal of the lower telescopic arm, there are two connections: one connection is that a fourth cascading connection terminal of a lower most balance unit of the upper telescopic arm is directly connected with a second cascading connection terminal of a higher most balance unit of the lower telescopic arm; the other connection is that a third cascading connection terminal of the lower most balance unit of the upper telescopic arm is connected to a first cascading connection terminal of the higher most balance unit of the lower telescopic arm through an inductor, a resistor, or a parallel circuit of an inductor and a resistor.

11. The converter bridge arm according to claim 4 , wherein, a cascading connection of a plurality of balance units includes a plurality of two adjacent units; any two adjacent units include a former unit and a latter unit; a third cascading connection terminal of the former unit is connected with a first cascading connection terminal of the latter unit through an inductor; a fourth cascading connection terminal of the former unit is connected with a second cascading connection terminal of the latter unit through an inductor (Ls 2 ); a relationship between the inductor (Ls 1 ) and the inductor (Ls 2 ) is one selected from the followings: (1) inductor (Ls 1 ) and inductor (Ls 2 ) are separate inductors; (2) inductor (Ls 1 ) and inductor (Ls 2 ) are coupled inductors, and magnetic fluxes of a voltage balanced current on an energy storage capacitor (C) are mutually enhanced in the two inductors; (3) inductor (Ls 1 ) and inductor (Ls 2 ) are separate inductors, and one of the two inductors is connected with a resistor (R) in parallel; and (4) inductor (Ls 1 ) and inductor (Ls 2 ) are coupled inductors, magnetic fluxes of a voltage balanced current on an energy storage capacitor (C) are mutually enhanced in the two inductors, and one of the two inductors is connected with a resistor (R) in parallel.

12. A circuit of the converter bridge arm according to claim 4 which has a conventional converter topology, wherein: a common bridge arm is replaced by a converter bridge arm, both the upper telescopic arm and the lower telescopic arm of the converter bridge arm are formed by a cascading connection of a plurality of balance asymmetrical units, thus a configuration of the circuit is selected from one of the followings: (1) a bidirectional DC/DC converter includes the converter bridge arm, a positive terminal and a negative terminal of the converter bridge arm are connected with positive and negative terminals of a first direct current source respectively, and a neutral point terminal of the converter bridge arm is connected with a filter inductor in series and then connected with a positive terminal of a second direct current source, the negative terminal of the converter bridge arm is connected with a negative terminal of the second direct current source; (2) a single-phase or multiphase DC/AC or AC/DC converter includes one or a plurality of converter bridge arms, positive and negative terminals of the converter bridge arms are connected in parallel respectively to serve as direct current positive and negative terminals, and neutral points of the converter bridge arms are alternating current terminals for various phases; and (3) a single-phase or multiphase back-to-back AC/DC/AC converter includes a plurality of converter bridge arms, positive and negative terminals of the converter bridge arms are connected in parallel respectively to serve as direct current positive and negative terminals, neutral points of a first group of converter bridge arms are connected with various phases of a first alternating current source respectively, and neutral points of a second group of converter bridge arms are connected with various phases of a second alternating current source respectively.

13. The converter bridge arm according to claim 4 , wherein a three-phase or multiphase converter is formed by further connection of one or a plurality of upper or lower telescopic arms in the converter bridge arm; the upper telescopic arms and the lower telescopic arms in the converter bridge arm are all formed by a cascading connection of balance symmetrical units; the cascading connection is one selected from followings: (1) positive and negative terminals of the converter bridge arm are connected with two phases of a three-phase power source, one end of a further connected upper or lower telescopic arm is connected with a neutral point terminal of the converter bridge arm, while the other end of the further connected upper or lower telescopic arm is connected with remaining phases of the three-phase power source, such that, a star converter is formed; a star multiphase converter is formed by further increasing the number of the telescopic arms; or (2) positive and negative terminals of the converter bridge arm are connected with a telescopic arm in parallel and connected with two phases of a three-phase power source respectively, a neutral point terminal of the converter bridge arm is connected with remaining phases of the three-phase power source, such that, a triangle converter is formed; and a polygon multiphase converter is formed by connecting a plurality of telescopic arms in series and then connecting these telescopic arms with the positive and negative terminals of the converter bridge arm in parallel.

14. An AC/AC converter made with the converter bridge arm according to claim 4 , includes one or a plurality of converter bridge arms, and the circuit configuration is one selected from followings: (1) positive and negative terminals of a single converter bridge arm are an alternating current port and a neutral point terminal and the terminal (N) are another alternating current port, such that, a single-phase AC/AC variable frequency converter is formed; (2) a multiphase alternating current port is led from positive and negative terminals of the converter bridge arms in accordance with a polygon or star connection method, and another multiphase alternating current port is led from neutral point terminals of the converter bridge arms, such that, a multiphase AC/AC variable frequency converter is formed; or (3) positive and negative terminals of a first group of three converter bridge arms are connected with various input phases respectively in accordance with a triangle or star connection method, and positive and negative terminals of a second group of three converter bridge arms are connected with various output phases respectively in accordance with a triangle or star connection method; neutral point terminals of two groups of converter bridge arms are connected with primary and secondary windings of a three-phase medium-frequency transformer respectively, such that, an electronic transformer is formed.

15. A converter control configuration based on the converter bridge arm according claim 4 , wherein: terminal voltages (Us) of the units in the upper and lower telescopic arms are controlled by regulating drive pulses of the switches, so as to control terminal voltages (Uu) and (Ud) of the upper telescopic arm and the lower telescopic arm; an average current (I PN ) passing between positive and negative terminals of the converter bridge arm is controlled by dynamically regulating a sum of the voltage (Uu) and the voltage (Ud), so as to control an average value of (Uc) of all the units in the converter bridge arm; regulation for voltage potential at an neutral point terminal is achieved by complementarily regulating the voltage (Uu) and the voltage (Ud); distribution of currents (I P ) and (I N ) of the upper telescopic arm and the lower telescopic arm is changed by dynamically regulating a relative magnitude of the voltage (Uu) and the voltage (Ud), so as to balance a difference between an average value of an voltage (Uc); and differences of the voltage (Uc) on an energy storage capacitor of the units in the telescopic arms are balanced by regulating a relative magnitude of average values of a terminal voltage (Us) of the units in the upper telescopic arm and the lower telescopic arm.

16. The converter control configuration according to claim 15 , wherein: the converter control configuration is one selected from followings: (1) a configuration of identical pulse phase is configured for the units in a same telescopic arm; (2) a configuration of phase-shift is configured for the units in a same telescopic arm; (3) a configuration of a sinusoidal pulse width modulation (SPWM) in which carriers are equally phase-shifted based upon angle of circumference is configured for the units in a same telescopic arm, and carriers phases of the corresponding units between the upper telescopic arm and the lower telescopic arm are complemented; or (4) a configuration of a three-phase DC/AC, AC/DC converter formed by three bridge arms, six units, which are located at same positions of the bridge arms, are grouped and controlled under a sinusoidal space vector pulse width modulation (SVPWM) mode, and modulated carriers of the units in the same telescopic arm are equally phase-shifted based upon angle of circumference.